Isolation and characterization of species-specific DNA probes from Taenia solium and Taenia saginata and their use in an egg detection assay.

ABSTRACT

Cysticercosis results from ingestion of the eggs of the tapeworm Taenia solium. Reduction of the incidence of human and swine cysticercosis requires identification and treatment of individuals who carry the adult tapeworm. T. solium and Taenia saginata eggs cannot be differentiated on the basis of morphology; thus, in order to improve existing methods for the diagnosis of taeniasis, we have developed highly sensitive, species-specific DNA probes which differentiate T. solium and T. saginata. Recombinant clones containing repetitive DNA sequences which hybridize specifically with genomic DNAs from either species were isolated and characterized. T. solium-specific DNA sequences contained complete and truncated forms of a tandemly repeated 158-bp DNA sequence. An unrelated T. saginata DNA sequence was also characterized and shown to encode a portion of the mitochondrial cytochrome c oxidase I gene. T. solium- and T. saginata-specific DNA probes did not hybridize in dot blot assays either with genomic DNA from the platyhelminths Taenia hydatigena, Taenia pisiformis, Taenia taeniaeformis, Echinococcus granulosus, and Schistosoma mansoni or with genomic DNA from other eukaryotes, including Saccharomyces cerevisiae, Candida albicans, Cryptosporidium parvum, Entamoeba histolytica, Trypanosoma gambiense, Trypanosoma brucei, and Giardia lamblia, Caenorhabditis elegans, and human DNA. By using these T. solium and T. saginata DNA probes, a rapid, highly sensitive and specific dot blot assay for the detection of T. solium eggs was developed.